B and T Cell Epitopes of the Incursionary Foot-and-Mouth Disease Virus Serotype SAT2 for Vaccine Development

Cell Culture Adaptive Amino Acid Substitutions in FMDV Structural Proteins: A Key Mechanism for Altered Receptor Tropism

The foot-and-mouth disease virus is a highly contagious and economically devastating virus of cloven-hooved animals, including cattle, buffalo, sheep, and goats, causing reduced animal productivity and posing international trade restrictions. For decades, chemically inactivated vaccines have been serving as the most effective strategy for the management of foot-and-mouth disease. Inactivated vaccines are commercially produced in cell culture systems, which require successful propagation and adaptation of field isolates, demanding a high cost and laborious time. Cell culture adaptation is chiefly indebted to amino acid substitutions in surface-exposed capsid proteins, altering the necessity of RGD-dependent receptors to heparan sulfate macromolecules for virus binding. Several amino acid substations in VP1, VP2, and VP3 capsid proteins of FMDV, both at structural and functional levels, have been characterized previously. This literature review combines frequently reported amino acid substitutions in virus capsid proteins, their critical roles in virus adaptation, and functional characterization of the substitutions. Furthermore, this data can facilitate molecular virologists to develop new vaccine strains against the foot-and-mouth disease virus, revolutionizing vaccinology via reverse genetic engineering and synthetic biology.

Recombinant bacteriophage T4 displaying key epitopes of the foot-and-mouth disease virus as a novel nanoparticle vaccine

Foot-and-mouth disease virus (FMDV) is a highly contagious pathogen that has caused significant economic losses in the livestock industry. Peptide vaccines engineered with the protective epitopes of FMDV have provided a safer alternative for disease prevention than the traditional inactivated vaccines. However, the immunogenicity of the peptide is usually poor and therefore an adjuvant is required. Here, we showed that recombinant T4 phages displaying the B-cell epitope of the FMDV VP1 protein (VP1130-158), without additional adjuvants, induced similar levels of antigen-specific IgG1 but higher levels of IgG2a compared to the peptide vaccine. Incorporation of a CD4+ T cell epitope, either 3A21-35 of FMDV 3A protein or P2830-844 of tetanus toxoid, further enhanced the immunogenicity of VP1-T4 phage nanoparticles. Interestingly, the extrinsic adjuvant cannot enhance the immunogenicity of the nanoparticles, indicating the intrinsic adjuvant activities of T4 phage. Furthermore, the recombinant T4 phage can be produced on a large scale within a short period of time at a relatively low-cost using Escherichia coli, heralding its potential in the development of a safe and effective FMDV vaccine.

Serological Conversion through a Second Exposure to Inactivated Foot-and-Mouth Disease Virus Expressing the JC Epitope on the Viral Surface

Foot-and-mouth disease (FMD) is a fatal contagious viral disease that affects cloven-hoofed animals and causes severe economic damage at the national level. There are seven serotypes of the causative foot-and-mouth disease virus (FMDV), and type O is responsible for serious outbreaks and shows a high incidence. Recently, the Cathay, Southeast Asia (SEA), and ME-SA (Middle East-South Asia) topotypes of type O have been found to frequently occur in Asia. Thus, it is necessary to develop candidate vaccines that afford protection against these three different topotypes. In this study, an experimental FMD vaccine was produced using a recombinant virus (TWN-JC) with the JC epitope (VP1 140-160 sequence of the O/SKR/Jincheon/2014) between amino acid 152 and 153 of VP1 in TWN-R. Immunization with this novel vaccine candidate was found to effectively protect mice against challenge with the three different topotype viruses. Neutralizing antibody titers were considerably higher after a second vaccination. The serological differences between the topotype strains were identified in guinea pigs and swine. In conclusion, a significant serological difference was observed at 56 days post-vaccination between animals that received the TWN-JC vaccine candidate and those that received the positive control virus (TWN-R). The TWN-JC vaccine candidate induced IFNγ and IL-12B.